In certain fluid flow applications, a propagating wave of energy is generated due to a sudden stoppage of fluid flow. This may be due to a sudden pump shut-down or a quick closing valve. This creates a backward surge or pulse of energy that can increase as it travels. This back surge carries with it a pressure spike and energy causing a vibration through the system sometimes known as “water hammer.” Water hammer can damage the piping system and cause premature fatigue on pipes, component and joints. The further the wave travels, the more damaging the generated energy becomes.
One attempted solution involves a cylindrical-type dampener attached to the pipe in which the backward energy pulse is traveling. However, these solutions to suffer the drawback that in order to create a minimal solution or to mitigate the pulse, the system has to be pressurized entirely in order to change the direction of the pulse or surge into the dampener. The backward pressure spike or surge will find the path of least resistance, which doesn't usually involve a change in direction into the dampener until the system has been pressurized. But at that point, the surge has hit all the pipes, joints, valves, etc., and some damage will already have been done.
Some conventional solutions involve fixed choke devices positioned in-line in the pipe. However, these devices only mitigate a small percentage of the backward surge or pulse. Additionally, these devices often cause a pressure drop in the system which could adversely affect the makeup of the fluid flowing through the pipe. For example, in a pumping system for liquid propane (LP), if the water hammer device causes too big of a pressure drop in the forward direction, then the fluid could actually gas off.